The invention is directed to a method for the automatic determination of the diameter of a round disk-like tool, particularly a saw blade for an automatic wall saw, which is driven by a motor.
The invention is further directed to a method for adjusting optimum cut parameters, particularly the cut length and cut depth, for an automatic wall saw.
An automatic wall saw is generally realized as a robot with two degrees of freedom. These degrees of freedom are the forward feed x of the drive unit on a carriage and the swiveling angle Φ of a swiveling arm which is articulated, for example, at a motor or gear unit housing, the saw blade being rotatably mounted at the free end of the swiveling arm. For an automatic sawing process in wall saws, it is necessary to know the diameter of the saw blade because the cut depth t and cut length, among others, depend on this. In addition, it is possible to adjust an optimal cutting speed when the diameter of the saw blade is known. This also applies in principle to smaller electric power tools such as circular saws, parting-off or angle grinders and the like.
It is known in electric power tools to provide the exchangeable tools with coding containing information about specific features of the tool. A readout device or sensor is associated with this coding so that selectable operating parameters of the drive unit can be optimized for the tool in question based on information specific to the tool. Different complementary pairings of coding and readout are known for this purpose, namely, mechanical, optical, magnetic, inductive or transponder-based.
For example, DE 37 20 512 A1 describes a hand-held device with a receptacle detachably connected to a drive shaft for tools whose insertion end has groove-shaped recesses engaging in radially displaceable locking elements in the tool receptacle. The locking elements are held in engagement with the tool by an actuating sleeve rotatably enclosing the tool receptacle. In order to disengage the lock, the actuating sleeve is rotated until the locking elements move radially outward into recesses in the actuating sleeve, thereby disengaging from the tool. Radially movable control elements in the tool receptacle are-arranged in a defined rotational position relative to the locking elements. Longitudinal grooves are associated with the control elements at the insertion end of the tool so that the control elements can penetrate into these longitudinal grooves in radial direction under the action of springs. Swiveling levers are associated with the control elements. These swiveling levers read off or measure the radial position of the control elements, one end of the swiveling levers being at a correspondingly changeable radial distance from a sensor which is positioned so as to be stationary in the device housing. When the tool receptacle rotates, these ends of the swiveling levers move past the sensor and therefore influence the sensor inductively. The ends of the levers can have working surfaces of different size which influence the sensors. Operating parameters of the device, e.g., the rotational speed and number of impacts in case of a drill hammer, are adjusted corresponding to the switching signals generated in the sensor.
The subject matter of DE 37 21 771 A1 is a hand-held device which likewise has a receptacle for tools that is detachably connected to a drive shaft. The insertion end of the tools is provided with an adapted receptacle body for the tool in question, whose working diameter can vary widely. For this reason, there are commonly two different diameters for this type of insertion end. In order to be able to use all of these tools with one hand-held device, two tool receptacles which are adapted to these different diameters can be selectively exchanged for one another and connected to the drive shaft so as to be fixed with respect to rotation relative to it. The locking elements engaging in the recesses of the tools are radially displaceable by means of a locking sleeve which is rotatable or displaceable relative to the receptacle body. Control elements which are radially displaceable relative to the locking sleeve are arranged in additional openings of the receptacle body. The control elements permit a rotation or displacement of the locking sleeve in a first radial position in which they penetrate into recesses formed at the tool and in a second radial position block any such movement of the locking sleeve. The locking elements and the control elements must be removed from the cross section intended for receiving the respective insertion end of the tools in order for a tool to be inserted into the receptacle, so that the locking sleeve is moved against a returning or restoring force until the locking elements and the control elements can move radially outward so as to snap into a widened area of the locking sleeve. When the tool is completely inserted into the tool receptacle, the locking sleeve is released and moves in the direction of its rest position under the action of the returning force.
Due to the great variety of working diameters of the tools that can be used with a tool receptacle of this kind, it is desirable to adapt the device to the capabilities of each tool. For this purpose, the locking sleeve and the device housing are provided with sensor elements which are associated with one another and which cooperate to adjust the device to the capacity suited to the tool as soon as the locking sleeve is in its rest position. There is no tool-specific adjustment of capacity at the device when tools not having these recesses associated with the control elements are inserted into the tool receptacle. In that case, the device is operated with a standardized operating characteristics setting. To enable diverse adjustments, a plurality of sensors can also be provided in combination with a plurality of control elements at the receptacle body and a plurality of recesses which are associated with the latter can be provided in the tool. Accordingly, the technical expenditure for this tool-oriented adjustment of the device is considerable.
DE 36 37 128 A1 describes an automatic, tool-specific adjustment of the operating characteristics of an electric drive device for exchangeable tools in which tool-specific data marks are arranged on the tool shaft to be uniformly distributed over its circumference. These data marks cooperate with a reading device which is built into the tool receptacle of the drive device to be fixed with respect to the device housing, such that when there is relative movement between the tool and work device the reading device generates an electric signal which adjusts the drive device to operating parameters corresponding to the tool by an electronic evaluating device. The data marks can comprise a sequence of notch-like recesses which are distributed over the circumference of the shaft and separated by webs that are left on the shaft diameter resulting in at least one data track comprising a sequence of associated recesses and webs with which, for example, an inductive sensor or an optical sensor in the reading device is associated.
A machine tool according to DE 196 29 623 A1 has a tool spindle with a receptacle for a rotary tool. A multispeed shifting device transmits the rotation of a drive shaft to the tool spindle in a rotational speed ratio that is determined by the effective gear in each instance. The rotary tool is provided with a code which can be sensed mechanically and which indicates a desired operating speed of the tool spindle. The code is sensed by a switching mechanism of the shifting gear unit such as a feeling pin guided axial to the tool spindle, such that there is no need for the user of the machine to be informed about the desired rotational speed and to adjust the machine correspondingly.
According to DE 43 12 162, an electric power tool, particularly for sawing, grinding and drilling, is outfitted with a stationary sensor, the driven tool, e.g., a saw blade, moving past this sensor so that a mark on the driven tool that is associated with the sensor can be sensed and data relating to this tool can be sent and processed by a control unit while working with the electric power tool to adjust the respective optimal operating parameters, particularly the rotational speed. The marks can be, for example, a sequence of projections, recesses, openings or contrasting color markings on the surface of the tool. The sensor can operate by optical, magnetic, inductive or capacitative sensing.
An example for the application of a transponder is found in DE 35 41 676 A1. A module having an electronically readable marking is arranged on the objects for general characterization and identification of objects, but particularly of equipment such as tools and workpiece carriers required in manufacturing processes. An evaluating device is provided with at least one receiver which reads the markings. Every module contains at least one oscillating circuit for generating a resonant frequency combination or frequency combination characteristic for it. The modules arranged on the object are selected in accordance with the elements required for indicating the identification of the object in the selected code. A pocket bore hole on the shaft of a tool, for example, can be associated with every module to hold the module.
Also, U.S. Pat. No. 4,742,470 describes a transponder which is arranged at a tool to be identified in an automated machine tool system and which can be interrogated by a receiver. An intended field of application is in machine tools which are digitally controlled by computers, known as CNC machines, and which have access to tools that are accommodated in a cartridge and have a standardized tool shaft. The machines can automatically remove the required tool from the cartridge and insert it into the drive spindle enabling programmed machining of a large number of different parts without the input of an operator. The transponder is interrogated by a receiver which preferably has read/write capabilities. The transponder to which signals are supplied sends the information contained in memory back to the receiver.
In principle, at least some of the known systems or methods briefly discussed above could also be used for automatically determining the diameter of a disk-shaped tool, particularly a saw blade. In every case, however, this would require additional devices, e.g., optical sensors, mechanical sensing devices or magnetic or electromechanical reading devices. Most of the known methods also require additional elements or specific modifications in the tools themselves.